ECMAScript target version mismatch with cicd env

### Subject of the issue

Our unit-tests with Circleci run in node12 which supports es2019. Our tsconfig target is es2020.

### Steps to reproduce

1. make a function that uses optional chaining
2. build
3. check the /dist folder, you'll see the optional chaining won't be downcompiled, as it's es2020 syntax.

### Expected behaviour

Optional chaining, non-nullish coalescing operator and others are all features of es2020. They're essential to write modern js. We should either bump the node version in cicd to 14 - 12 being past its end of life anyway - or set a es2019 target in our tsconfig.

### Actual behaviour

Any function using es2020 features unsupported by node12 will fail in testing.